When using MySQl in PHP, if you want to get the column values as an array, then simply change the fetch_argument in the PDO fetchAll call like this:
<?php
$recipes = $result->fetchAll(PDO::FETCH_COLUMN);
?>
Using PDO::FETCH_COLUMN will return the column as an array instead of the regular, 2d array when using FETCH_ASSOC. You can also specify which columns values you want, returns the first column values if you don’t specify. Read more about PDO Statement fetchAll here.